Why are helicopters hovering up above Coatesville PA area?

Well just in case you missed. This morning at around 3AM August 15th 2013 Thursday, a trailer truck crash roll over to its side blocking both lanes of the highway 30 bypass. Around 4AM three helicopters all from news media agencies came and been hovering for hours. They just left. Traffic closed both lanes and took 6 hours to clear now back to normal 🙂 thanks good goodness it was cleared before traffic hours if not it could been worst, no injuries reported just the truck driver few scratches, and big tow truck had to be called to move the big rig to the side of the road and somewhere else later. Although Chemical was carried but not toxic.